Waveguide structure utilizing roller spring supports

ABSTRACT

A waveguide structure utilizes roller spring supports for supporting a waveguide in a conduit to simultaneously provide a compliant support and allow free relative longitudinal movement between the waveguide and the conduit. A tension band having a plurality of spring assemblies integrally formed therewith is fastened about the periphery of the waveguide. Rollers are mounted on the spring assemblies in contact with the conduit to allow free relative longitudinal movement of the waveguide and conduit. The spring assemblies provide a soft compliant support throughout a range of deflections accommodating the worst expected thermal loading conditions in route bends. Under higher loading the spring assemblies bottom out and provide a stiff support to prevent further radial deflection of the waveguide with respect to the conduit.

llnie States ent 1 Lutchanslty WAVEGUIDE STRUCTURE UTILIZING ROLLER SPRING SUPPORTS Inventor: Milton Lutchansky, Randolph Township, Morris County, NJ.

Bell Telephone Laboratories, Incorporated, Berkeley Heights, NJ.

Filed: Mar. 14, 1973 Appl. No.: 341,286

Assignee:

U.S. Cl. 333/98 R, 333/98 M, 138/113, 248/54 Int. Cl H011) l/30, F161 7/00 Field of Search ,138/106, 113, 114; 248/54 R, 54 CS; 333/98 R, 98 M References Cited UNITED STATES PATENTS Bankert, Jr. et al. 333/98 R Primary Examiner-Rudolph V. Rolinec Assistant ExaminerWm. l-l. Punter Attorney- A. D. Hooper [57] ABSTRACT A waveguide structure utilizes roller spring supports for supporting a waveguide in a conduit to simultaneously provide a compliant support and allow free relative longitudinal movement between the waveguide and the conduit. A tension band having a plurality of spring assemblies integrally formed therewith is fastened about the periphery of the waveguide. Rollers are mounted on the spring assemblies in contact with the conduit to allow free relative longitudinal movement of the waveguide and conduit. The spring assemblies provide a soft compliant support throughout a range of deflections accommodating the worst expected thermal loading conditions in route bends. Under higher loading the spring assemblies bottom out and provide a stiff support to prevent further radial deflection of the waveguide with respect to the conduit.

10 Claims, 10 Drawing Figures WNFEHJAM 15 new FIG.a

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WAVEGUIDE STRUCTURE UTILIZING ROLLER SPRING SUPPORTS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to waveguide transmission systems and more particularly to a waveguide structure utilizing roller spring supports for supporting a waveguide within a conduit.

2. Description of the Prior Art It is generally expected that long-distance waveguide lines will be buried and accordingly the waveguide will be enclosed in a protective sheath or conduit. Much effort has been directed toward systems for supporting the waveguide within the sheath as evidenced by US. Pat. Nos. 3,007,122; 3,605,046; and 3,609,603 and copending applications Ser. Nos. 205,796 filed Dec. 8, 1971 now U.S. Pat. No. 3,750,058 and 208,207 filed Dec. 15, 1971, now U.S. Pat. No. 3,748,606 respectively, and all assigned to the assignee of this invention. Such support systems must simultaneously satisfy the conflicting requirements of being soft enough to filter or isolate the waveguide from deformations in the sheath while being stiff enough to limit the radial deflection of the waveguide sufficiently to avoid deleterious contact with the sheath when the waveguide is subjected to stresses from thermal loadings in route bends.

The foregoing support systems appear adequate when the waveguide and conduit are initially installed as a unit so that there is no necessity for any significant amount of relative longitudinal movement between the waveguide and sheath. However, under some conditions it appears desirable to initially install the sheath only and then subsequently install the waveguide therein. For example, the installation of the sheath may possibly be done at a much faster rate than installation of the waveguide. Thus, it would be economically undesirable to make the entire installation operation dependent upon the relatively slow rate of the waveguide installation. As another example, it might be desirable to install long lengths of conduit during the summer months when the soil is workable so that the waveguide could be installed therein at a slower rate on a year around basis. The waveguide would be installed in the previously laid conduit by pushing or pulling the waveguide through the conduit from one access area to another. The previously described support systems will not permit the required amount of relative longitudinal motion for such installation without requiring that excessive push or pull forces be applied to the waveguide.

Attempts have also been made to provide simple roller supports for allowing insertion of pipes such as waveguide in previously installed conduit. However, applicant is aware of no support system which simultaneously provides a compliant support satisfying the foregoing requirements for filtering the effects of conduit deformation under thermal and weight loading while allowing relative longitudinal movement of the waveguide.

Accordingly, it is an object of this invention to provide a compliant waveguide support system of relatively high load carrying capability which will allow installation of the waveguide in a previously installed sheath or conduit.

It is another object of this invention to provide a compliant system for supporting a waveguide within a conduit which will allow substantial relative longitudinal motion between the waveguide and the conduit.

SUMMARY OF THE INVENTION The foregoing objects and others are achieved in accordance with the invention by the utilization of roller spring supports. Each support comprises a tension band which is wrapped about the conduit. The band is configured to limit the tension therein to a level which will not produce deleterious diametrical distortions in the waveguide. A plurality of spring supports are integrally formed transverse to the tension band about the periphery of the waveguide. Rollers are mounted on these supports to contact the conduit and support the waveguide therein and to provide for free relative longitudinal movement between the waveguide and the conduit. The spring supports provide a low spring constant, high load carrying support throughout a range of deflection which accomodates the worst expected thermal loading conditions in route bends. Thereafter the spring supports present a very stiff support to prevent plastic deformation of the spring supports and deleterious contact between the waveguide and the conduit.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be more fully comprehended from the following detailed description and accompanying drawing in which:

FIG. 1 is a longitudinal partly sectional representation of a waveguide system utilizing the support system of this invention;

FIG. 2 is an enlarged view of a section of FIG. 1 including a single support;

FIG. 3 is a transverse cross-sectional view of the system of FIG. 1;

FIG. 4 is an enlarged view of a spring assembly utilized in the roller spring support;

FIG. 5 is a sectional view along lines 5-5 of FIG. 4;

FIG. 6 is a view of the support following the initial step in the fabrication thereof; and

FIGS. 7A7D are schematic representations of the installation of the tension band portion of the support about a waveguide section.

DETAILED DESCRIPTION As shown in FIG. 1, sections of waveguide 2 and 4 are joined at flanges 6 and 8 and installed in a conduit or sheath 10 such as by pushing or pulling the previously joined waveguide sections 2 and 4 into the previously installed conduit 10. Waveguide sections 2 and 4 are supported in conduit 10 by roller spring supports 12 so that the waveguide sections 2 and 4 and flanges 6 and 8 do not normally contact conduit 12. Roller spring supports 12 filter the deformations of conduit l0 and also permit free relative longitudinal movement of sections 2 and 4 with respect to conduit 10.

As shown more fully in FIGS. 2 and 3, each support 112 comprises a tension band 20 wrapped about the periphery of waveguide section 4 and having four spring assemblies 22 conneced thereto at substantially equal angular spacings about the periphery of section 4. As shown in FIG. 4, each spring assembly 22 is formed from wo substantially U-shaped springs 24 and 26 integrally formed on and extending outward from opposite edges of band 20. Springs 24 and 26 are folded back at an angle less than at bends 25 and 27, respectively, so that the ends of associated springs 24 and 26 overlap over the centerline of band 20 with spring 24 being on the outside or over spring 26 at the overlap. This forms a spring assembly 22 which can be deflected radially inward toward waveguide 4 in response to a radial force thereon thereby providing a compliant support.

On the overlapping portion of spring 24 two upstanding flanges 30 and 32 are formed. Flanges 30 and 32 include notches 34 and 36 therein near the tops in which respective ends 38 and 40 of a mounting rod or axle of a roller 42 are rotatably mounted. Roller 42 contacts the inner periphery of conduit to support waveguide section 4 therein in such a manner as to permit relative movement between conduit 10 and section 4.

The overlapping end of spring 26 is turned or bent downward to form a lip or stop 44. When a radial load or force is applied to roller 42 such as by the deformation of conduit 10 or by thermal contraction of the waveguide which causes movement of the waveguide toward the inner curvature of a bend, the top portions of springs 24 and 26 are deflected downward thereby. During the initial portion of such deflection, spring assembly 22 exhibits a relatively low, substantially constant spring constant which provides a soft support and good filtering to isolate waveguide 4 from conduit 10. If the deflection continues, stop 44 will eventually contact the bottom portion of springs 24 or band and thereafter will present a very stiff support which prevents further radial deflection of waveguide 4 with respect to conduit 10 to prevent deleterious contact therewith. The amount of deflection 46 which spring assembly 22 can undergo before stop 44 bottoms out or contacts the bottom portion of springs 24 or band 20 depends upon the angle of bends and 27 and the length or height 45 of stop 44. These parameters and the thickness, length and width of springs 24 and 26 are chosen to meet the two basic requirements of allowing sufficient radial deflection of waveguide 4 to accommodate the worst expected thermally induced transverse or radial forces encountered in route bends and preventing deflection of springs 24 and 26 beyond the yield point of the material utilized therein.

FIG. 5 illustrates how springs 24 and 26 are joined at their overlapping ends to prevent separation thereof during any subsequent deflection. Springs 24 and 26 include respective detents 50 and 52 which mesh together. Spring 26 includes two recesses 54 along the edges thereof into which depending tabs 56 from spring 24 are inserted and crimped to prevent separation.

Tension band 20 and spring assemblies 22 can be made as a one piece unit from readily available sheet or strip stock metal. FIG. 6 shows the initial configuration which can be formed by a stamping or punch press operation on a flat sheet of stock. By cold-working machining operations which will be apparent to those skilled in the art, springs 24 and 26 are subsequently bent into the compliant overlapping configuration illustrated in FIGS. 1 through 5 and roller 42 is installed thereon. Springs 24 and 26 are advantageously initially overbent at bends 25 and 27 until stop 44 bottoms out. Upon release of the forming force springs 24 and 26 spring back to the configuration of FIG. 4. This insures that any subsequent deflection of spring assembly 22 occurs in the spring-back zone of springs 24 and 26 thereby providing linear behavior during deflection and preventing the possibility of exceeding the yield point of the material utilized in the springs.

As previously mentioned, tension band 20 is designed to prevent the application of excessive forces which would produce degrading diametrical distortions in the waveguide when band 20 is installed thereabout. For this purpose one end thereof band 20 has a tongue 60 with a detent 62 therein for providing more stiffness or resistance to bending joined by a notched section or neck 64 to a short beam section 66 connected to the body of band 20 at point 67. Tongue 60 is formed at substantially right angles to the remainder of band 20 by bending at point 67 where beam section 66 joins band 20 prior to installation about the waveguide. An upturned lip 68 is also formed prior to installation on the opposite end of beam 20 during the cold-working operations previously mentioned. This end also includes an opening 70 to be discussed later. As schematically illustrated in FIGS. 7A-7D, band 20 is initially wrapped about waveguide 4 and tongue 60 is engaged in lip 68. A force F is then applied against lip 68 in a direction to cause it to fold down over tongue 60. Band 20 initially yields at neck 64 because of the lower resistance to bending at that point forming a plastic hinge, i.e., a point of plastic yielding, thereat as shown in FIG. 7B. Continued rotation downward as shown in FIG. 7C produces a second plastic hinge at point 67 when the tension in band 20 exceeds a predetermined amount because greater bending moments are applied to point 67 than to the remainder of beam 66. Still further rotation as shown in FIG. 7D causes tongue 60 to fold upward into opening 70 where it becomes locked into position because the tension in band 20 is applied in such a manner as to prevent tongue 60 from rotating in an unlocking or opening direction. The plastic yielding at points 64 and 67 limits the tension in band 20 to a level which does not produce degrading diametrical distortions in waveguide section 4. For example, the dimensions of the various sections of band 20 can advantageously be designed to limit the tension therein to a value of no greater than 50 pounds which will produce diametrical distortions no greater than approximately one micron which is acceptable.

The roller spring supports of this invention are dis crete supports. Accordingly, there will be deflections of the waveguide between these discrete supports in accordance with well-known beam deflection principles because of weight loading and thermally produced loadings or forces on the waveguide. The desired mode of transmission in the waveguide, which is expected to be the TE mode, will experience unacceptable degradation into spurious modes if any of the mechanical deflections in the waveguide correspond to any of the beat wavelengths between the desired mode and the spurious modes of the frequencies of interest. Of particular importance are the spurious modes TM and TE Accordingly, the spacings between the roller spring supports 12 along the waveguide are made shorter than the shortest beat wavelength between TE. and both TM and TE so that the resulting deflections between supports produces no significant degradation in transmission Utilizing the supports 12 of this invention, it is expected that as much as one-mile lengths of waveguide can be pushed into previously laid conduit. This represents a significant advantage over existing support systems which do not simultaneously provide a compliant support and permit longitudinal movement of the waveguide relative to the conduit.

While the invention has been described with reference to a specific embodiment thereof, it is to be understood that various modifications thereto might be made without departing from its spirit and scope.

What is claimed is:

1. Apparatus for supporting a section of waveguide within a section of protective conduit, comprising, in combination:

a plurality of tension bands each having edges mounted circumferentially about said waveguide at spaced points therealong;

a plurality of substantially U-shaped members having first and second ends, each of said members being connected to one edge of said band by said first end and extending outward therefrom in opposing relationship to an associated one of said members connected to the other of said edges, said second end of each of said members being connected to said second end of said associated member in spaced relationship to said band to form a spring support which can be deflected radially inward toward said band; and

a roller rotatably mounted on said spring support for movably contacting said conduit, whereby said waveguide is supported in said conduit by a compliant support which permits free relative movement between said waveguide and said conduit.

2. Apparatus in accordance with claim 1 wherein said second end of one of said members overlays said second end of said associated member, said second end of said one member has upstanding flanges thereon with openings therethrough, said roller having an axle mounted in said openings; and

said second end of said associated member has a depending lip thereon for limiting the amount of deflection of said spring supporttoward said band.

3. Apparatus in accordance with claim 2 wherein said lip contacts said band to prevent further deflection of said spring support toward said band; and

said lip has a height which limits said deflection to an amount less than that which would cause plastic yielding of said spring support.

4. Apparatus in accordance with claim 1 including four of said members along each of said edges which form four of said supports located at substantially equal angular spacings about said waveguide.

5. Apparatus in accordance with claim 1 wherein said band has two ends, said first end includes a tongue portion, a beam portion having a first end connected to the remainder of said band and a neck portion joining said tongue portion to said beam portion, said first end being initially disposed substantially perpendicular to the remainder of said band;

said second end includes a lip adapted to receive said tongue portion therein when said band is mounted about said waveguide, said lip portion being adapted to rotate over said tongue portion to lock said band in position, said neck portion having a lower resistance to bending than the remainder of said first end whereby said tongue portion rotates about said neck portion when said lip portion is rotated thereover to cause rotation of said beam portion about said first end when said band has a tension therein greater than a predetermined level.

6. Apparatus in accordance with claim 5 wherein said neck portion and said beam portion have bending resistances which limit the tension in said band to a value no greater than 50 pounds.

7. Apparatus in accordance with claim 1 wherein said waveguide can transmit a plurality of wave modes including the TE circular mode and the TM and TE spurious modes having beat wavelengths with said TE mode so that said TE mode interchanges energy with said spurious modes when said waveguide has mechanical deformations therein corresponding to said beat wavelengths, and wherein the spacings of said bands along said waveguide are less than the shortest one of said beat wavelengths.

8. A waveguide structure, comprising, in combination:

a section of waveguide;

a section of protective conduit surrounding said waveguide;

a plurality of spring supports mounted about the periphery of said waveguide at spaced points therealong, said supports being responsive to an inwardly directed force thereon in deflect inwardly toward said waveguide; and

a roller rotatably mounted on said supports and adapted to deflect therewith for movably contacting said conduit and supporting said waveguide in spaced relation thereto, whereby said waveguide is supported by a compliant support which permits free relative longitudinal movement thereof with respect to said conduit.

9. Apparatus for use in supporting a first member in spaced relationship within a surrounding member comprising:

a tension band having edges adapted for being wrapped circumferentially about said first member;

a plurality of substantially U-shaped members having first and second ends, each of said members being connected to one edge of said band by said first end and extending outward therefrom in opposing relationship to an associated one of said members connected to the other of said edges, said second end of each of said members being connected to said second end of said associated member in spaced relationship to said band to form a spring support which can be deflected radially inward toward said band; and

contact means mounted on said spring support and adapted for movably contacting said surrounding member when said apparatus is mounted on said first member within said surrounding member, whereby said apparatus can provide a compliant support which allows relative movement between said first member and said surrounding member.

10. Apparatus in accordance with claim 9 wherein said contact means comprises a roller adapted for establishing rolling contact with said surrounding member. 

1. Apparatus for supporting a section of waveguide within a section of protective conduit, comprising, in combination: a plurality of tension bands each having edges mounted circumferentially about said waveguide at spaced points therealong; a plurality of substantially U-shaped members having first and second ends, each of said members being connected to one edge of said band by said first end and extending outward therefrom in opposing relationship to an associated one of said members connected to the other of said edges, said second end of each of said members being connected to said seCond end of said associated member in spaced relationship to said band to form a spring support which can be deflected radially inward toward said band; and a roller rotatably mounted on said spring support for movably contacting said conduit, whereby said waveguide is supported in said conduit by a compliant support which permits free relative movement between said waveguide and said conduit.
 2. Apparatus in accordance with claim 1 wherein said second end of one of said members overlays said second end of said associated member, said second end of said one member has upstanding flanges thereon with openings therethrough, said roller having an axle mounted in said openings; and said second end of said associated member has a depending lip thereon for limiting the amount of deflection of said spring support toward said band.
 3. Apparatus in accordance with claim 2 wherein said lip contacts said band to prevent further deflection of said spring support toward said band; and said lip has a height which limits said deflection to an amount less than that which would cause plastic yielding of said spring support.
 4. Apparatus in accordance with claim 1 including four of said members along each of said edges which form four of said supports located at substantially equal angular spacings about said waveguide.
 5. Apparatus in accordance with claim 1 wherein said band has two ends, said first end includes a tongue portion, a beam portion having a first end connected to the remainder of said band and a neck portion joining said tongue portion to said beam portion, said first end being initially disposed substantially perpendicular to the remainder of said band; said second end includes a lip adapted to receive said tongue portion therein when said band is mounted about said waveguide, said lip portion being adapted to rotate over said tongue portion to lock said band in position, said neck portion having a lower resistance to bending than the remainder of said first end whereby said tongue portion rotates about said neck portion when said lip portion is rotated thereover to cause rotation of said beam portion about said first end when said band has a tension therein greater than a predetermined level.
 6. Apparatus in accordance with claim 5 wherein said neck portion and said beam portion have bending resistances which limit the tension in said band to a value no greater than 50 pounds.
 7. Apparatus in accordance with claim 1 wherein said waveguide can transmit a plurality of wave modes including the TE01 circular mode and the TM11 and TE12 spurious modes having beat wavelengths with said TE01 mode so that said TE01 mode interchanges energy with said spurious modes when said waveguide has mechanical deformations therein corresponding to said beat wavelengths, and wherein the spacings of said bands along said waveguide are less than the shortest one of said beat wavelengths.
 8. A waveguide structure, comprising, in combination: a section of waveguide; a section of protective conduit surrounding said waveguide; a plurality of spring supports mounted about the periphery of said waveguide at spaced points therealong, said supports being responsive to an inwardly directed force thereon to deflect inwardly toward said waveguide; and a roller rotatably mounted on said supports and adapted to deflect therewith for movably contacting said conduit and supporting said waveguide in spaced relation thereto, whereby said waveguide is supported by a compliant support which permits free relative longitudinal movement thereof with respect to said conduit.
 9. Apparatus for use in supporting a first member in spaced relationship within a surrounding member comprising: a tension band having edges adapted for being wrapped circumferentially about said first member; a plurality of substantially U-shaped members having first and second ends, each of said members being connected to onE edge of said band by said first end and extending outward therefrom in opposing relationship to an associated one of said members connected to the other of said edges, said second end of each of said members being connected to said second end of said associated member in spaced relationship to said band to form a spring support which can be deflected radially inward toward said band; and contact means mounted on said spring support and adapted for movably contacting said surrounding member when said apparatus is mounted on said first member within said surrounding member, whereby said apparatus can provide a compliant support which allows relative movement between said first member and said surrounding member.
 10. Apparatus in accordance with claim 9 wherein said contact means comprises a roller adapted for establishing rolling contact with said surrounding member. 